Apparatus and methods for pre-heating water with air conditioning unit or heat pump

ABSTRACT

Water heater apparatus includes a tank for storing water; a heat exchanger associated with the tank and being operative to receive refrigerant and transfer heat therefrom to the tank, the heat exchanger representatively being a heat conductive tube externally wrapped around the tank in heat conductive contact therewith; air conditioning apparatus operative to utilize refrigerant flowing through a refrigerant circuit portion of the air conditioning apparatus, the refrigerant circuit portion being in fluid communication with the heat exchanger; and a control system operative to selectively cause a portion of the flowing refrigerant to pass through the heat exchanger, or cause essentially the entire flow of the refrigerant to bypass the heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of the filing date of provisional U.S. patent application No. 61/779,087 filed Mar. 13, 2013. The entire disclosure of the provisional application is hereby incorporated herein by this reference.

BACKGROUND OF THE INVENTION

Various apparatus and methods have previously been proposed for preheating water in a water heater tank using refrigerant from air conditioning apparatus such as an air conditioner with a non-reversible refrigerant circuit, or a heat pump having a reversible refrigerant circuit. However, such previously proposed apparatus and methods have often proven to be undesirably complex and expensive for use in many applications. It would be desirable to provide such apparatus and methods that efficiently utilize air conditioning apparatus refrigerant heat to preheat water. It is to this goal that the present invention is primarily directed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an air conditioner/water heater circuit embodying principles of the present invention, with the air conditioner providing only conditioned space air cooling;

FIG. 2 is a schematic diagram similar to that in FIG. 1, but with the air conditioner being in its air cooling mode and also providing refrigerant heat to a single water heater;

FIG. 3 is a schematic diagram similar to that in FIG. 2, but with the air conditioner providing refrigerant heat to one of the water heater tanks in a two water heater tank arrangement;

FIG. 4 is a schematic diagram of a heat pump/water heater circuit embodying principles of the present invention, with the heat pump being in its air cooling mode;

FIG. 5 is a schematic diagram similar to that in FIG. 4, but with the heat pump being in its air cooling mode and also providing refrigerant heat to the water heater;

FIG. 6 is a schematic diagram similar to that in FIG. 4, but with the heat pump being in its air heating mode without also providing refrigerant heat to the water heater; and

FIG. 7 is a schematic diagram similar to that in FIG. 4, but with the heat pump being in its air heating mode and also providing refrigerant heat to the water heater.

DETAILED DESCRIPTION

As used herein, the term “air conditioning apparatus” encompasses apparatus useable to change the temperature of air being delivered to a conditioned space and having an associated refrigerant circuit. Thus, “air conditioning apparatus” may comprise (1) an air conditioning unit (or “air conditioner”) having a non-reversible refrigerant circuit that may be used to cool air delivered to a conditioned space, or (2) a heat pump having a reversible refrigerant circuit that may be used to heat or cool air delivered to a conditioned space.

Typical residential air conditioning apparatus removes heat from a house and transfers it to the environment outside the house. In carrying out principles of the present invention, a portion of that heat may be captured and used to pre-heat water in the home's water heater to a temperature below the set point temperature of the water heater. The electric element(s) or gas burner in the water heater provides additional heat to bring the water temperature up to the set point temperature of the water heater. A heat pump in either its heating or cooling mode may also be used to pre-heat water in a water heater in accordance with principles of the present invention.

An air conditioner/water heater circuit 10 embodying principles of the present invention is schematically depicted in FIGS. 1 and 2 and includes (1) an air conditioner 12 having an outdoor condensing unit 14 and an indoor coil unit 16, and (2) an associated water heater 18 which, representatively, may be a gas-fired or electric water heater. In FIG. 1 the air conditioner 12 is in an air cooling only mode, and in FIG. 2 is in an air cooling mode and further provides supplemental, refrigerant-based heat to the water heater 18. The various functions of the air conditioner/water heater circuit 10 are controlled by a schematically depicted electronic control circuit 20 (shown only in FIG. 1) which operates various subsequently described components of the overall circuit 10.

Referring initially to FIG. 1, the outdoor condensing unit 14 includes a condenser coil 22 and associated condenser fan 24, and a compressor 26. The condenser coil 22 and compressor 26 are coupled, as shown, by a refrigerant tubing circuit 28 having suction and liquid line portions 30 and 32, to the indoor unit evaporator coil 34 and to a heat conductive refrigeration tube spiral-wrapped around a metal tank portion 36 of the water heater 18 and serving as a refrigerant-to-tank water heat exchanger 38 for the water heater 18.

Operatively linked to the electronic control system 20 are (1) an electronically controlled regulator valve 40 with an associated refrigerant temperature sensor 42 installed as shown in the refrigerant tubing circuit 28 within the condensing unit 14, (2) an electronically controlled regulator valve 44 and an associated refrigerant temperature sensor 46 installed as shown in the refrigerant tubing circuit 28 adjacent the refrigerant inlet 48 of the coiled heat exchanger 38, and (3) a normally open solenoid valve 50 installed in a refrigerant bypass line 32 a between the heat exchanger inlet 48 and the heat exchanger refrigerant outlet 52. As illustrated in FIG. 1, water to be heated is flowed into the water heater tank 36 via a water inlet pipe 54, and, in response to a heated water demand, is discharged from the tank 36 via a hot water supply pipe 56.

Still referring to FIG. 1, with the air conditioner 12 in its air cooling only mode, without the water heater 18 needing refrigerant heat to be transferred to the water in its tank 36 via the heat exchanger 38, gaseous refrigerant if transferred from the evaporator coil 34 to the compressor 26 via the suction line 30, with the compressor 26 causing hot refrigerant liquid to flow through and be cooled by the condenser coil 22. The electronic control system 20 maintains the solenoid valve 50 in its normally open position, and holds the regulator valves 40,44 in closed positions such that liquid exiting the condenser coil 22 flows through the open solenoid valve 50, bypassing the water heater heat exchanger 38, and flows, via tubing portion 32, through the expansion valve 58 into and through the evaporator coil 34. Cooled gaseous refrigerant discharged from the evaporator coil 34 is then returned to the compressor 26 via suction line 30. Air (not shown) flowed over the evaporator coil 34 is cooled and flowed to a conditioned space served by the air conditioner 12.

Turning now to FIG. 2, when the water heater 18 requires refrigerant heat (as determined by a non-illustrated temperature sensor in a bottom portion of the tank 36), the control system 20 (FIG. 1) appropriately positions the various previously described valves 40,44,50 to which it is linked to cause a portion of the hot refrigerant traversing the tubing circuit 28 to pass through the heat exchanger 38, thereby adding refrigerant heat to the water in the water heater tank 36, before joining the hot refrigerant flow exiting the valve 50 and bypassing the heat exchanger 38 for flow therewith to the evaporator coil 34. When the control system 20 detects that the water heater 18 no longer needs refrigerant heat, it returns the air conditioner 12 to its FIG. 1 air cooling mode in which all of the refrigerant flow traversing the tubing circuit 28 bypasses the water heater coiled tube heat exchanger 38 for the additional electric or gas-fired water heater 18 a.

The overall air conditioner/water heater circuit 10 a schematically depicted in FIG. 3 is identical to the previously described air conditioner/water heater circuit 10 with the exceptions that (1) an additional water heater 18 a, having either electric or gas heating apparatus associated therewith, but without an associated coiled tube refrigerant-to-water heat exchanger, is connected in series with the previously described water heater 18 such that water exiting the water heater 18 via pipe 56 is flowed through the additional water heater 18 a and then discharged therefrom through a hot water outlet pipe 56 a, and (2) the water heater 18 is not provided with electric or gas heat, but receives only refrigerant heat via its tubing heat exchanger portion 38, thus functioning solely as a water preheating device.

This two tank configuration allows hot water to be stored when the air conditioner unit 12 (or a heat pump as later described herein) is running during times when there is little or no demand for hot water, thereby providing additional low cost hot water capacity during periods of time when the demand for hot water is high. It also improves the efficiency of the air conditioning unit or heat pump compared to the previously described single tank arrangement since the water in the preheater tank 18 will usually be at a lower temperature than the water temperature in the main tank 18 a during periods of time when there is little or demand for hot water.

A heat pump/water heater circuit 60 embodying principles of the present invention is schematically depicted in FIGS. 4-7 and includes (1) a heat pump 62 having an outdoor unit 64 and an indoor coil unit 66, and (2) an associated water heater 68 which, representatively, may be a gas-fired or electric water heater. In FIG. 4 the heat pump 62 is in an air cooling only mode. In FIG. 5 the heat pump 62 is in an air cooling mode and further provides supplemental, refrigerant-based water preheating to the water heater 68. In FIG. 6 the heat pump 62 is in an air heating only mode. In FIG. 7 the heat pump 62 is in an air heating mode and further provides supplemental, refrigerant-based water preheating to the water heater 68. The various functions of the heat pump/water heater circuit 60 are controlled by a schematically depicted electronic control circuit 70 (shown only in FIG. 4) which operates various subsequently described components of the circuit 60.

As shown in FIGS. 4-7, the outdoor unit 64 includes a condenser coil 72 and associated fan 74, and a compressor 76. The condenser coil 72 and compressor 76 are coupled, as shown, by a refrigerant tubing circuit 78 having line portions 80 and 82, to the indoor unit evaporator coil 84 and to a heat conductive copper tube spiral-wrapped around a metal tank portion 86 of the water heater 68 and serving as a refrigerant-to-tank water heat exchanger 88 for the water heater 68.

The outdoor unit 64 has a reversing valve 90, an electronically controlled regulator valve 92, and a normally closed solenoid valve 94 connected as shown in the tubing circuit 78 and operatively linked to the electronic control system 70. The indoor coil unit 66 has a normally closed solenoid valve 98 and a normally open solenoid valve 100 connected as shown in the tubing circuit 78 and operatively linked to the electronic control system 70. The water heater 68 has a temperature sensor 102, an electronically controlled regulator valve 104, a normally open solenoid valve 106, and a normally closed solenoid valve 108 connected as shown in the tubing circuit 78 and operatively linked to the electronic control system 70.

Turning now to FIG. 4, with the heat pump/water heater system 60 in an air cooling only mode, the electronic control system sets the previously described valve components in the tubing circuit 78 in a manner such that the compressor 76 causes refrigerant discharged therefrom to flow, via tubing portion 80 of the tubing circuit 78, sequentially through the condenser coil 72 to the water heater 68 where the refrigerant, due to the closure of the regulator valve 104, bypasses the heat exchanger 88 through the open solenoid valve 106. The liquid refrigerant then flows through tubing portion 80 through the expansion valve 110 into and through the evaporator coil 84, and finally (as gaseous refrigerant) flows back to the compressor 76. Air (not shown) flowed over the evaporator coil 84 is cooled and flowed to a conditioned space served by the heat pump 62.

When a temperature sensor (not shown) of the water heater 68 calls for refrigerant heat while the heat pump 62 is in a cooling mode thereof, the electronic control system 70 appropriately repositions the water heater regulator valve 104 and the normally open solenoid valve 106 such a portion of the hot refrigerant flows through the heat exchanger 88 and back into the tubing portion 80, thereby adding refrigerant heat to the tank water, with the remainder of the hot refrigerant approaching the water heater 68 bypassing it and flowing with the refrigerant exiting the heat exchanger 88 through the expansion valve 110 and the evaporator coil 84 back to the compressor 76 via the tubing portion 82.

With the heat pump/water heater system 60 switched to its air heating only mode as shown in FIG. 6, the electronic control system 70 (FIG. 4) switches the reversing valve 90, and adjusts other tubing circuit valve components, in a manner such that hot refrigerant discharged from the compressor 76 initially flows, via tubing portion 82 of the tubing circuit 78, to the evaporator coil 84 (now functioning as an air heating coil). A portion of this refrigerant flow bypasses the coil 84 (through partially opened valve 98) and enters tubing portion 80 downstream of the coil 84, with the refrigerant flow exiting the coil 84 via the expansion valve 110 mixing with the bypassing refrigerant for delivery therewith to the water heater 68 via the tubing portion 80. This mixed refrigerant flow, via the closure of the valve 104, entirely bypasses the heat exchanger 88, via the open solenoid valve 106, and then sequentially flows, via the tubing portion 80 and the opened valve 94, through the expansion valve portion (not shown) of the condenser coil 72, the condenser coil 72 (which extracts heat from outside air), and then back to the compressor 76.

Finally, as shown in FIG. 7, if the electronic control system 70 (FIG. 4) detects that the water heater 68 needs refrigerant heat when the heat pump 62 is in an air heating mode, the control system 70 appropriately adjusts the water heater valves 104,106,108 in a manner such that a portion of the mixed refrigerant flow to the water heater 68 flows through the coiled tubing heat exchanger 88 to add refrigerant heat to the tank water, with the balance of the mixed refrigerant flow bypassing the heat exchanger 88 via the valve 106.

In the case of either the previously described air conditioning unit 12 or the heat pump 62, when the temperature of the water in the lower portion of the water heater tank reaches a predetermined temperature, appropriate ones of the valve components in the outdoor unit and water heater are positioned by the electronic control system (20 or 70 as the case may be) to return the air conditioning unit or heat pump system to its normal operational mode (cooling or heating without refrigerant heat transfer to the water heater tank water).

In optional constructions of the air conditioning and heat pump systems 10,60 described above, the electronically controlled regulator valves may be replaced with fixed orifice solenoid valves, and the flow of hot refrigerant to the water heater refrigerant-to-water heat exchanger coils may instead be regulated by the compressor discharge (head) pressure using an outdoor or indoor fan speed controller which is, in turn, controlled by the sensed water temperature in the water heater tank.

The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims. 

What is claimed is:
 1. Apparatus for heating water, comprising: a tank for storing water; a heat exchanger associated with said tank and being operative to receive refrigerant and transfer heat therefrom to said tank; air conditioning apparatus operative to utilize refrigerant flowing through a refrigerant circuit portion of said air conditioning apparatus to regulate the temperature of air being delivered to a conditioned space, said refrigerant circuit portion being in fluid communication with said heat exchanger; and a control system operative to selectively (1) cause a portion of the flowing refrigerant to pass through said heat exchanger, or (2) cause essentially the entire flow of said refrigerant to bypass said heat exchanger.
 2. The apparatus for heating water of claim 1 wherein: said air conditioning apparatus comprises an air conditioning unit.
 3. The apparatus for heating water of claim 1 wherein: said air conditioning apparatus comprises a heat pump.
 4. The apparatus for heating water of claim 1 wherein: said heat exchanger comprises a heat conductive tube externally wrapped around said tank in heat conductive contact therewith.
 5. The apparatus for heating water of claim 1 wherein: said tank is a first tank for storing water, and said apparatus for heating water further comprises a second tank for storing water, said second tank for storing water being piped in series with said first tank for storing water, and said heat exchanger comprises a heat conductive tube externally wrapped around said first tank in heat conductive contact therewith.
 6. The apparatus for heating water of claim 5 wherein: said heat exchanger is the sole source of heating water in said first tank.
 7. The apparatus for heating water of claim 6 wherein: said second tank is devoid of an external refrigerant-to-water heat exchanger.
 8. The apparatus for heating water of claim 1 wherein: said tank for storing water is a water heater tank.
 9. The apparatus for heating water of claim 8 wherein: said tank for storing water is a gas-fired water heater tank.
 10. The apparatus for heating water of claim 8 wherein: said tank for storing water is an electric water heater tank.
 11. A method of heating water stored in a tank, comprising: placing a heat exchanger in heat conductive contact with said tank; providing air conditioning apparatus operative to utilize refrigerant flowing through a refrigerant circuit portion of said air conditioning apparatus to regulate the temperature of air being delivered to a conditioned space, said refrigerant circuit portion being in fluid communication with said heat exchanger; and controlling said air conditioning apparatus in a manner selectively (1) causing a portion of the flowing refrigerant to pass through said heat exchanger and transfer refrigerant to said tank, or (2) causing essentially the entire flow of said refrigerant to bypass said tank.
 12. The method of claim 11 wherein: said placing step includes the step of externally wrapping a heat conductive tube around at least a portion of said tank.
 13. The method of claim 11 wherein said providing step includes the step of: providing an air conditioning unit.
 14. The method of claim 11 wherein said providing step includes the step of: providing a heat pump. 